Silver halide photographic material showing improved latent image stability

ABSTRACT

A silver halide photosensitive material has been provided which has, in at least one light-sensitive emulsion layer thereof, a silver halide emulsion comprising grains or crystals rich in silver chloride, which grains have been chemically sensitized in a specific way in the presence of a substituted phenyl-mercaptotetrazole compound according to the formula represented in the detailed description and in the claims, said compound having been added at the end of chemical sensitization, and, moreover the method of preparing said material has been claimed.

FIELD OF THE INVENTION

[0001] The present invention relates in general to a silver halidelight-sensitive material and in particular to a photographic “MotionPicture Print Film”. More specifically this invention relates to aMotion Picture Print Film characterized by an excellent latent imagestability, otherwise expressed as showing little change in sensitivityin the time interval between exposure and processing.

BACKGROUND OF THE INVENTION

[0002] A Motion Picture Print film, the film that is shown in movietheatres, contains besides the motion picture image optical sound tracksalong at least one edge of the film. In order to optimize the visualguality of the motion picture image as well as the sound quality of thesound track recorded on a motion picture, the motion picture and soundtracks are first typically captured or recorded on separatephotosensitive films as negative images, and the resulting negatives arethen printed in synchronization on the motion picture film to formpositive images. This printing is performed in so-called printlaboratories.

[0003] In normal conditions the time between printing (exposure of themotion picture film) and processing is limited. It is however possiblethat between exposure and processing, the time delay can amount toseveral days. In such conditions it is important that the sensitivity ofthe motion picture film does not change between exposure and processing,or otherwise expressed, that the latent image formed upon exposure doesnot alter between exposure and processing.

[0004] Photographic Motion Picture Print Films typically use highchloride emulsions to enable rapid processing.

[0005] Since the blue-sensitive layer in a typical Motion Picture Filmis situated nearest to the undercoat, a high sensitive emulsion isneeded which consists almost entirely of silver chloride in order toenable rapid processing.

[0006] Such high sensitive emulsions emulsions rich in silver chloridecan however show a large change in sensitivity in the time intervalbetween exposure and development.

OBJECTS OF THE INVENTION

[0007] It is an object of the present invention to provide a method ofpreparing a material excellent in rapid processing ability and showinglittle change of the sensitivity between the time of exposure and theprocessing, even if this time amounts to several days.

[0008] More particularly an object of the present invention is toprovide a method of processing a color print photographic material by arapid color development system.

[0009] Futher objects will become apparent from the descriptionhereinafter.

SUMMARY OF THE INVENTION

[0010] The above mentioned objects have been realized by providing asilver halide photosensitive material which has in at least onelight-sensitive emulsion layer thereof a silver halide emulsioncomprising grains or crystals rich in silver chloride, wherein saidgrains have been chemically sensitized in the presence of a substitutedphenyl-mercaptotetrazole compound, and more preferably anacetamidophenyl mercaptotetrazole compound, according to the formularepresented in the detailed description and in the claims. A method ofpreparing such an emulsion preferably comprises the steps ofprecipitating cubic crystals rich in silver chloride (up to 100 mole %of AgCl) by double jet in an aqueous medium containing a protectivecolloid, flocculating, washing and redispersing said emulsion byaddition of a binder material; adjusting pH and pAg up to suitablevalues and adding, prior to chemical sensitization, a compound releasingiodide ions, followed, after digestion, by consecutively adding, aschemical sensitizing agents, a gold compound, an oxidizing compound anda compound releasing sulphur;

[0011] chemically sensitizing said cubic emulsion crystals;characterized by the step of adding, immediately after ending saidchemically sensitizing step, before cooling, a compound according to thegeneral formula (I)

(I)

[0012] wherein R represents a substituted aryl and wherein M representsa hydrogen atom, an alkali metal atom or an ammonium group.

[0013] A silver halide material prepared according to the method of thepresent invention has also been claimed and, more particularly, a colorprint material, wherein the emulsion prepared according to the method ofthe present invention is coated in at least one of the emulsion layerssensitive to a different wavelength range.

[0014] The particular agent added to the emulsion before chemicallysensitizing it corresponds to the general formula (I).

[0015] Specific features for preferred embodiments of the invention areset out in the dependent claims.

[0016] Further advantages and embodiments of the present invention willbecome apparent from the following description.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The method of the present invention thus applied as set forthhereinbefore suppresses the increase in the fog density, further savingthe photographic sensitivity in an environment wherein changes of heatand humidity appear during storage or preservation of the material and,more particularly, between the time of exposure and the processing ofsaid material.

[0018] Moreover the effect of the invention resides in a quickprocessability (rapid processing application) by this invention,providing a low fog and high speed.

[0019] The compound added at the end of chemical sensitization step isthe compound according to the general formula (I) hereinafter

[0020] wherein R represents a substituted aryl and wherein M representsa hydrogen atom, an alkali metal atom or an ammonium group.

[0021] Preferred substituted mercapto-tetrazole compounds according tothe general formula (I), are represented hereinafter in the formulae(I.1-I.12):

[0022] According to the present invention one or more of those compoundsare added in a preferred total amount in a range of from 0.01 up to 1mmole per mole of silver halide.

[0023] According to a preferred embodiment of the present invention,immediately after ending chemical sensitization, thus just beforestarting cooling, during and/or at the end of the cooling process of thechemically sensitized emulsion, at least one of the mercaptote-trazolecompounds, and more preferred, the acetamidophenyl mercapto-tetrazolecompounds (see more particularly the compounds I.1, I.4, I.6, I.10 andI.12) are added, in order to fully attain the objects of the presentinvention.

[0024] The method of preparing an emulsion according to the presentinvention starts with the preparation of an emulsion in an aqueousmedium containing a protective colloid, said method comprising the stepsof precipitating cubic emulsion crystals rich in silverchloride,flocculating, washing and redispersing by addition of a bindermaterial; adjusting pH and pAg; adding, prior to chemical sensitization,a compound releasing iodide ions; adding as chemical sensitizing agentsconsecutively, a gold compound, an oxidizing compound and a compoundreleasing sulphur; chemically sensitizing by digestion at a controlledtemperature said cubic emulsion crystals; and as characterizing featurethat, immediately after ending said chemically sensitizing step bystarting cooling the emulsion to a lower temperature than the controlledtemperature during the effective chemical ripening or sensitizationprocess, addition of a substituted phenyl-mercaptotetrazole compoundaccording to formula (I), set forth above, proceeds.

[0025] During the whole preparation process of the cubic grain emulsiontemperature controll is very important: before starting precipitatingcubic crystals rich in silver chloride (up to 100 mole % of AgCl) bydouble jet in an aqueous medium containing a protective colloid, thereaction vessel containing said aqueous medium is already temperaturecontrolled, at least at a temperature exceeding the temperature at whichthe protective colloid solidifies. As, according to the method of thepresent invention said protective colloid is selected from the groupconsisting of gelatin (whether or not chemically modified) , silica sol,(cationic) (oxidized or non-oxidized) starch or mixtures thereof, beingrepresentative, but not limitative for organic and inorganic bindersrespectively, it depends on the choice thereof what temperature for thereaction vessel is chosen in order to prepare a homogeneous aqueousmedium wherein the precipitation reaction can start. In general in thepreparation step of the reaction vessel a temperature of about 40° C. upto 50° C. is chosen when gelatin, whether or not modified as e.g.phthaloyl or (phenyl)carbamoyl gelatin, whether or not oxidized in orderto reduce the amount of methionin therein, and whether or notdemineralized in order to have a lower calcium ion content, is taken as(most preferred) protective colloid.

[0026] A preferred precipitation technique in order to get cubiccrystals rich in silver chloride is the double-jet method, wherein thesilver ion concentration is controlled during the precipitation andwherein the flow rate of the reacting solutions is enhanced as theprecipitation proceeds. The flow rate is controlled at such a rate thatno renucleation appears. This method offers the possiblity to getwell-defined crystals having a regular cubic habit within a shortprecipitation time, which is also dependent on the reaction temperaturein the reaction vessel, which is normally increased before startingprecipitation from about 40° C.-45° C. up to 55-65° C.

[0027] According to the method of the present invention, theprecipitation step is performed in order to get cubic emulsion crystalsrich in silver chloride having an average edge length of from 0.1 μm upto 1.0 μm (more preferably from 0.2 up to 0.8 μm).

[0028] Further according to the method of the present invention saidcubic emulsion grains rich in silver chloride have at least 50 mole % ofsilver chloride, based on silver; and silver bromide, if present, in amolar amount of not more than 20 mole %, more preferably not more than10 mole %, based on silver. Although the silver bromide content may bedivided homogeneously over the whole cubic crystal volume, a so-calledlocalization phase with high silver-bromide content may be present as aninternal shell in the cubic crystal. It should however be avoided to gettoo high a silver bromide content as pressure, applied to such asensitive material, may cause desensitization. So the silver bromidecontent of a localization phase with high silver bromide contentpreferably is in the range between 20-50 mole % range. Such a silverbromide content of a localized phase with high silver bromide contentcan be analyzed using an X-ray diffraction method.

[0029] As a binder material the preferred gelatin may further bereplaced in part or integrally by synthetic, semi-synthetic, or naturalpolymers. Synthetic substitutes for gelatin are e.g. polyvinyl alcohol,poly-N-vinyl pyrrolidone, polyvinyl imidazole, polyvinyl pyrazole,polyacrylamide, polyacrylic acid, and derivatives thereof, in particularcopolymers thereof. Natural substitutes for gelatin are e.g. otherproteins such as zein, albumin and casein, cellulose, saccharides,starch, and alginates. In general, the semi-synthetic substitutes forgelatin are modified natural products e.g. gelatin derivatives obtainedby conversion of gelatin with alkylating or acylating agents, bygrafting of polymerizable monomers on gelatin or prehardened gelatinswith blocked functional groups as a consequence of this prehardeningtreatment, and cellulose derivatives such as hydroxyalkyl cellulose,carboxymethyl cellulose, phthaloyl cellulose, and cellulose sulphates.The binder should of course dispose of an acceptably high number offunctional groups, which by reaction with an appropriate hardening agentcan provide a sufficiently resistant layer after emulsion coating. Suchfunctional groups are especially the amino groups, but also carboxylicgroups, hydroxy groups, and active methylene groups. Another substitutefor gelatin may be silica as has been described in the published EP-A's0 392 092, 0 517 961, 0 528 476, 0 649 051 and 0 704 749. Moreparticularly when colloidal silica sol is chosen as a protective colloidthe reaction vessel can be prepared at lower temperatures as has beenset forth in e.g. EP-A 0 682 287 and in the corresponding U.S. Pat.No.5,543,284. In these patents the particular conditions have beendescribed in which cubic silver chloride emulsions having grains of awell-defined grain size are prepared. According to the method of thepresent invention the said binder material is a hydrophilic colloidalpolymeric binder selected from the group consisting of gelatin,poly-N-vinylpyrrolidone, dextranes, polyacrylamide, cellulose compoundsand derivatives thereof and copolymers of vinylidenechloride-methylacrylate-itaconic acid ormethyl(meth)acrylate-butadiene-itaconic acid or a mixture (or mixtures)thereof.

[0030] If gelatin is further used, besides being used as protectivecolloid in the precipitation of cubic grains rich in silver chloride,the said gelatin may be used as peptizer or binder material afterflocculation and washing. In order to get a qualitatively goodflocculate flocculating agents as e.g. polystyrene sulphonic acid, etc.,may be added before or after acidifying the emulsion, preferably at theprecipitation temperature, followed by cooling up to e.g. roomtemperature and starting washing of the flocculate by means of a scraperudder. By decantation of the aqueous phase rich in alkali halide(especially potassium chloride) salts and repeating addition ofdemineralized water and further washing (at least two, preferably threetimes or even more), this process can be performed discontinuously, inbatch. Other possibilities are offered by filtration techniques, e.g. bydialysis, ultrafiltration etc. so that the emulsion may be washed to adesired pAg value without the requirement to be redispersed afterwards.Emulsion flocculates are preferably washed out by the addition ofwell-determined amounts of demineralized water, whether or not dopedwith small amounts of water-soluble salts like e.g. sodium or potassiumchloride. By consecutive washing procedures in batch or continuouslywashing or by means of diafiltration or ultrafiltration the desired pHand/or pAg of the emulsion is reached in order to get a peptizedemulsion, ready for getting chemically sensitized.

[0031] In case of gelatin for use as a protective colloid and/or bindermaterial the ratio by weigth of gelatin to silver (expressed asequivalent amount of silver nitrate) is called “gesi” and is acharacteristic feature of the emulsion. So after precipitation a gesivalue of e.g. 0.15-0.25 may be reached, whereas after peptization, byaddition of gelatin peptizer at an increased temperature up to about38-48° C., the gesi value may have been increased up to a value of from0.40 up to 0.60.

[0032] Further gelatin may be used as a binder material in the coatedlayers of the material (wherein a gesi value up to a value in the rangefrom 0.8 to 1.2 may be calculated). The said gelatin providing colloidalstability of the cubic emulsion grains, peptizing ability or coatingability may be lime-treated or acid-treated. The preparation of suchgelatin types has been described in e.g. “The Science and Technology ofGelatin”, edited by A. G. Ward and A. Courts, Academic Press 1977, page295 and next pages. The gelatin may also be an enzyme-treated gelatin asdescribed in Bull. Soc. Sci. Phot. Japan, N° 16, page 30 (1966).Preferably use is made of photographically inert gelatin in order to adda reproducible amount of chemical sensitizers in the following chemicalsensitization step, wherefor the temperature of the reaction vesselshould be increased up to 50-70° C., more preferably up to 50-60° C.

[0033] According to the method of the present invention, prior tochemical sensitization a compound releasing iodide ions is added,followed by a digestion period (about at least 5 minutes), beforestarting the chemical sensitization procedure, wherein said compoundreleasing iodide ions is selected from the group consisting of an alkaliiodide salt, an I₃-complex and a fine-grained silver iodide emulsion,having emulsion grains of not more than 0.050 μm. Those compound(s) is(are), according to the method of the present invention added in anamount in order to have an average amount of iodide in the cubiccrystals rich in silver chloride of not more than 3 mole %, based onsilver. In a more preferred embodiment an average amount of iodidepresent in the cubic crystals rich in silver chloride does not exceed 1mole % and is even more preferably in the range between 0.05 and 0.5mole %.

[0034] After digestion of the emulsion crystals rich in silver chlorideand enriched in silver iodide as set forth above, according the methodof the present invention the step is performed of adding as chemicalsensitizing agents consecutively, a gold compound, an oxidizing compoundand a compound releasing sulphur, followed by chemically sensitizing bydigestion (during a time dependent on the reaction temperature, whichmay vary from less than 1 hour at 70° C. up to about 4 hours at 50° C.)at a controlled temperature of said cubic emulsion crystals.

[0035] According to the method of the present invention as chemicalsensitizing agents are added consecutively, a gold compound (like goldchloride acid or gold thiocyanide complex), an oxidizing compound (likethe preferred toluene thiosulphonic acid salt, used as weakly oxidizingagent) and a compound releasing sulphur (like the preferred sodiumthiosulphate pentahydrate). It is self-explaining that the compoundsbetween brackets are not limited thereto. Moreover it is not excluded,in order to get an enhanced speed to make use of selenium compounds ase.g. triphenyl phosphor-selenide or even tellurium compounds, whereinsaid selenium and/or tellurium compounds may replace sulphur compoundspartially. It is further not excluded to add small amounts (e.g. from0.5 to 20 μmole per mole of silver) of iridium compounds (as e.g.potassium hexachloroiridate(III)) during and/or at the end of theprecipitation step and/or in the chemical ripening step as this may leadto a positive effect on processing latitude, in that less differences insensitivity and gradation are observed after fluctuations in shortdeveloping times within a range of 5 seconds and in processingtemperature within a range of about 5° C. Supplying an iridium compoundmay appear just before supply of the silver for forming a localizedphase under presence of an iridium compound, or immediately after saidsupply. E.g. when forming the localization phase with high silverbromide content by adding a water-soluble bromide solution, addinganother solution which the solution was made to contain an iridiumcompound beforehand, or contained the iridium compound simultaneously isperformed preferably.

[0036] Other suitable dopants used during precipitation or chemicalripening of cubic crystals rich in silver chloride may be Fe, Co, Ni,Ru, Rh, Pd, Os, Pt, Pb, Cd, Hg, Tl and Au.

[0037] A last step, of utmost importance in order to reach the objectsof the present invention is the step of adding, immediately after endingsaid chemically sensitizing (digestion) step, of one or moremercaptotetrazole compounds according to the general formula (I) as hasbeen extensively been set out before. The terminology “after ending saidchemically sensitizing step” has, according to the method of the presentinvention, to be understood as adding said compound(s) just before,during or at the end of the cooling step following the digestion at thewell-controlled higher temperatures as indicated above. In a preferredembodiment said compound(s) is added just before starting cooling theemulsion. Normally the chemically sensitized emulsion is cooled up to45-38° C., followed by addition, if required, of further stabilizingcompounds.

[0038] According to the present invention a silver halide material isprovided, comprising one or more emulsions prepared according to themethod described above, wherein said material is a color print material.It is not excluded however to use an emulsion, prepared according to themethod of the present invention in other silver halide materials as e.g.a sound recording material, a black-and-white single-side coatedradiographic, (micro)graphic or laser recording material. Preferablysaid material has a transparent support, selected from the group ofsupport materials consisting of cellulose nitrate, cellulose acetate,polyvinylacetal, polystyrene, polyethylene terephthalate, poly(ethylenenaphthalate), polycarbonate film and glass; polyethylene terephthalate(PET) being most preferred.

[0039] As has been mentioned in the background of the invention in oneembodiment a silver halide material, wherein an emulsion preparedaccording to the present invention is present, is a color printmaterial. Therein the emulsion prepared according to the method of thepresent invention is preferably coated in the blue sensitive layerthereof. In that case the emulsion is spectrally sensitized by additionof a blue sensitizing dye of the merocyanine type, given hereinafter andin the Examples (S-1), and wherein, in the alternative, the K⁺-saltthereof may be used.

[0040] Photographic silver halide emulsion materials or elementsaccording to the present invention, in favor of sharpness or imagedefinition, comprise an antihalation undercoat or layer in order toreduce light scattering, wherein said antihalation undercoat is indirect contact with the subbing layer at the light-sensitive side of thetransparent support or is separated from it by a thin indermediategelatin layer. Advantages offered by antihalation layers are e.g.well-known from microfilms and from radiographic applications, offeringa solution for the problem of image definition in circumstances whereinvery high demands are posed as in single-side coated recording materialsfor mammography (see e.g. EP-A's 0 610 609,0 712 036 and 0 874 275)brought into contact with an intensifying screen at the side of the filmsupport having the light-sensitive emulsion layer(s) or for laserrecording as e.g. described in EP-A 0 610 608 and 0 794 456 for theregistration of digitally stored images. As a function of the processingtimes and as a function of the need to have processed images free fromresidual stain or color the antihalation layer is present in the backinglayer (for rapid processing applications) or as an antihalationundercoat at the light-sensitive side, wherein, from the point of viewof reduction of light scattering, presence of an antihalation undercoatat the light-sensitive side is preferred.

[0041] Antihalation layers and dyes, useful in the material or elementof the present invention, are e.g. merostyryl dyes, oxonol dyes,pyrazolones, pyrrols, thiophenes, etc., as those described in EP-A's 0489 973, 0 586 748, 0 587 229, 0 587 230, 0 656 401, 0 724 191, 0 781816 and 0 786 497.

[0042] Antihalation dyes, present in the antihalation undercoat coveringthe subbing layer at the light-sensitive side of the support of thematerial according to the present invention are non-spectrallysensitizing dyes which are widely used in photographic elements in orderto absorb reflected and scattered light, in a limited or very broadwavelength range. Examples of the said dyes have been described e.g. inU.S. Pat. Nos. 3,560,214 and 4,857,446 and in EP-A's given above. Thefilter or accutance dye(s) can be coated in layers of photographicelements in the form as has been described in EP-A's 0 384 633, 0 323729, 0 274 723, 0 276 566, 0 351 593; in U.S. Pat. Nos. 4,900,653;4,904,565; 4,949,654; 4,940,654; 4,948,717; 4,988,611 and 4,803,150; inResearch Disclosure Item 19551 (July 1980); in EP-A 0 401 709 and inU.S. Pat. No. 2,527,583, these examples however being not limitative.More than one antihalation layer is optionally present, e.g. inmultilayer materials wherein the light-sensitive layer, as set forthhereinbefore, is part of a multilayer arrangement, optionally includingone or more intermediate layers between light-sensitive emulsion layers,wherein said emulsion layers have been made sensitive by spectralsensitization, to differing wavelength ranges, e.g. being sensitive toblue, green and red light as is well-known from color sensitivematerials, and wherein the said intermediate layers may containantihalation dyes in order to enhance sharpness or image definition in alimited wavelength range as described e.g. in EP-A 0 252 550 for colorprint materials and in EP-A 0 582 000 for color negative recordingmaterials.

[0043] According to the present invention an element is provided,wherein said antihalation undercoat comprises one or more dye(s), atleast one yellow non-diffusing dye that absorbs blue light and isremovable and/or decolorizable in a processing bath, and is chosen fromthe group consisting of merostyryl dyes and monomethine oxonol dyes.Preferably said merostyryl dyes are pyrazolone-5 merostyryl dyes havinga hydroxybenzal moiety and at least one carboxy or carbamoyl group onthe pyrazolone ring or symmetrical monomethine oxonols of pyrazolone.Particularly preferred is a yellow non-diffusing merostyryl dye (D-I)(gelatinous or colloidal silica) solid particle dispersion, as disclosede.g. in EP-A 0 569 074.

[0044] According to another embodiment of the present invention anelement is provided, wherein said element is a motion picture projectioncolor print film material, comprising a transparent film support andcoated thereon in succession, a blue-sensitive silver halide emulsionlayer comprising a yellow-forming coupler, a red-sensitized silverhalide emulsion layer comprising a cyan-forming coupler, an intermediatelayer, a green-sensitized silver halide emulsion layer comprising amagenta-forming coupler, and an antistress layer, wherein between saidsupport and said blue-sensitive silver halide emulsion layer a yellowantihalation undercoat is provided, which comprises at least one yellownon-diffusing dye that absorbs blue light and is removable and/ordecolorizable in a processing bath. As already set forth hereinbeforesaid at least one dye is preferably chosen from the group consisting ofa merostyryl dye and a monomethine oxonol dye, preferably being a(symmetrical) monomethine oxonol, and even more preferably apyrazolone-type monomethine oxonol, whereas preferred merostyryl dyesare of the pyrazolone-5-type, having a hydroxybenzal moiety and at leastone carboxy or carbamoyl group on the pyrazolone ring.

[0045] In still another embodiment said element is a color print filmmaterial, wherein between said blue-sensitive silver halide emulsionlayer and said red-sensitized silver halide emulsion layer a bluishantihalation intermediate layer is provided, which comprises at leastone blue non-diffusing dye that absorbs red light and is removableand/or decolorizable in a processing bath. Said at least one bluenon-diffusing dye is at least one pentamethine oxonol-type barbituricacid derivative dye, without however being limited thereto.

[0046] Preferred pentamethine oxonols of the barbituric acid typepreferably have at least one halogen atom, hydroxy, alkyl, alkoxy,carboxy,carbamoyl, sulphamoyl, alkoxycarbonyl, aryloxycarbonyl,alkoxysulphonyl, aryloxysulphonol, and heterocyclylsulphonyl, e.g.o-sulphamoyl-phenyl, p-methoxy-phenyl, and 3-hydroxy-4-carboxyphenylgroups. As an antihalation dye in a layer under the blue-sensitive layerthe preferred pentamethine oxonol dye (D-III) may advantageously beused, as illustrated in the Examples, without however being limitedthereto, as has been illustrated in EP-A 0 252 550 and the correspondingU.S. Pat. No. 4,770,984, wherein the preferred layer arrangement isclaimed.

[0047] In one embodiment of the present invention as it is an object toprovide a photographic film material wherein an emulsion is present,prepared according to the method of the present invention and whereinsaid emulsion is preferably coated in the blue sensitive layer thereof,and as moreover in a preferred embodiment said film material is a motionpicture print film, without a “carbon black” backing layer, which doesnot show, after processing, problems of loss of conductivity and loss ofdurability, especially with respect to scratching stability, said filmmaterial comprises, on a light-sensitive side of a transparent polyestersupport, in order, an electrically conductive subbing layer, anantihalation undercoat, a light-sensitive emulsion layer or multilayerarrangement, optionally including one or more intermediate,non-light-sensitive layers between emulsion layers in said multilayerarrangement, and a protective overcoat; and on a backing layer sideopposite thereto, in order, a subbing layer containing a lubricant and atopcoat layer, wherein, on the light-sensitive side of said element saidsubbing layer comprises an antistatic agent providing a substantiallyunchanged electrical resistivity of the said element before and afterprocessing of said material, and said antihalation undercoat optionallycomprises a high temperature boiling solvent; and wherein on the backinglayer side a friction coefficient of the backing layer versus stainlesssteel remains unchanged in the range between 0.20 and 0.30 before andafter processing of said material, even after removal of the saidtopcoat layer during processing in an alkaline developer.

[0048] The conductive subbing layer coated on the light-sensitive sideof the transparent polyester support shows about unchanged antistaticproperties due to the presence of an electronically conductive compoundproviding, before an after processing, where the electrical resistivityof this subbing layer is situated between 1×10⁵ and 1×10¹² Ω/□, morepreferably between 1×10⁷ and 1×10¹⁰ Ω/□, resulting in an electricalresistivity of the emulsion side of the element or material between1×10⁹ and 1×10¹⁴ Ω/□. The expression “substantially unchanged” indicatesthat changes in electrical resistivity are limited, in that differencesbefore and after processing are less than a factor of 100 (10²) Ω/□, andmore preferably less than a factor 10 Ω/□. In such an electricallyconductive subbing layer showing fairly unchanged antistatic propertiesan electrically-conductive agent is dispersed in a binder, theelectrically conductive agent being selected from the group consistingof electronic conductive metal-containing particles, metal oxidescontaining oxygen deficiencies, conductive nitrides, conductivecarbides, conductive bromides, fibrous electronic conductive powders,conductive polyacetylenes, conductive polythiophenes and conductivepolypyrroles, wherein polythiophenes, and more particularly PEDT (polyethylene dioxy thiophene) is most preferred. Electrically-conductiveagents may be present in amounts of from 0.5 mg/m2 to about 1000 mg/m2,depending on coating ability.

[0049] In the backing layer of the materials according to the presentinvention substantially changed electrical resistivity is measuredbefore and after processing, due to presence of electrically-conductiveagents dispersed in a binder, like the electrically conductive agentcomprising inorganic salts, alkali metal salts, ionic conductivepolymers, polymeric electrolytes containing alkali metal salts orcolloidal metal oxide sols, and wherein the binder further comprisesinterpolymers of ethylenically unsaturated monomers, cellulosederivatives, polyurethanes, polyesters, hydrophilic colloids, polyvinylalcohol or polyvinyl pyrrolidone. The electrically-conductive layer orlayers not having permanent antistatic properties further comprisecross-linking agents coating aids, surfactants, dispersing aids,coalescing aids, biocides, matte particles or lubricants. Thanks moreparticularly to the presence of a lubricant in the subbing layer at theside of the backing layer opposite to the light-sensitive side of thepolyester support and to the removal during processing of the topcoatlayer only, on the said backing layer side, the friction coefficient ofthe backing layer versus stainless steel remains about unchanged in therange between 0.20 and 0.30, which is an indispensble asset in order toavoid problems during manufacturing, i.a. during processing of theexposed film material as well as during projection of the processedmaterial) of the film, more particularly with respect to scratchability.

[0050] Otherwise presence of a high temperature boiling solvent,preferably in an amount of from 0.1 to 0.5 g/m², in the antihalationundercoat at the light-sensitive side of the polyester support, and,optionally, in an amount of from 0.2 to 1.0 g/m² in the blue-sensitiveemulsion layer of a color print material, provides an optimized lasersubtitling quality, whereas presence of permanent antistatic agent(s) inthe subbing layer avoids charging of the layers and dust attraction,both measures avoiding optically disturbing effects.

[0051] With respect to laser subtitling ability of color printmaterials—extensively set out in EP-A 0 782 045, corresponding with U.S.Pat. No. 5,981,155 and the high quality, i.a. good definition of thefigures, burned through the whole layer package of the color printmaterial can thus be obtained. All those features, providing anexcellent color print materials have been extensively described in EP-A1 202 115.

[0052] In another embodiment the photographic element according to thepresent invention comprises a support, at least one silver halide imageforming layer superposed on the support, a first transparentelectrically conductive layer comprising an electrical resistivity ofless than 1×10⁹ Ω/□ before photographic processing and an electricalresistivity of greater than 1×10¹¹ Ω/□ after photographic processing;and a second transparent electrically conducting layer comprising anelectrical resistivity of between 1×10⁹ Ω/□ and 10¹¹ Ω/□ both before andafter photographic processing as has been set out in U.S. Pat. No.6,140,030.

[0053] In a preferred embodiment of the present invention wherein thematerial is a color print material, processing proceeds in automaticprocessors. In case of a color print material, it is desirable to carryout bleaching fixing processing after color development from the purposeof quick processing. When especially the cubic grain emulsion rich insilver chloride, as for pH of a bleach fix bath, about 6.5 or less isdesirable for good desilvering purposes, whereas about at most 6.0 iseven more preferred.

[0054] The multi-layered color print material, as preferred according tothe present invention, is preferably used in combination with a negativeworking black-and-white silver halide motion picture sound recordingfilm in order to provide the color print film with a soundtrack of highquality. Said sound recording film preferably comprises a supportbearing at least one silver halide emulsion layer, wherein said film isspectrally sensitized both above and below 600 nm as disclosed in U.S.Pat. No. 5,955,255, thus being panchromatically sensitized as previouslydescribed in GB 449,546 and the corresponding FR 784,027. Such film maybe used for recording multiple optical soundtracks by exposing said filmwith a first source of radiation having a peak wavelength of less thanor equal to 600 nm, recording a second digital soundtrack by exposingsaid film with a second source of radiation having a peak wavelength ofgreater than 600 nm, and processing said exposed film to form first andsecond digital soundtrack silver images. Suitable antihalation dyes,selected e.g. from the dyes or pigments given hereinbefore may beadvantageously be coated in an antihalation undercoat of that soundrecording film. Typical black- and-white sound recording films designedfor recording analog soundtracks comprise a relatively fine grain,having e.g. a grain size less than 0.35 μm for a monodispersed silverhalide emulsion, which provides a high contrast overall gradient beinggreater than 3.7, more preferably greater than 3.8 and even morepreferably greater than 3.9, desirable for recording the soundtrack withsharp edges. In order to reach such high gradations in a shortprocessing time it is advantageous to develop said sound recording filmhaving fine emulsion grains in a rapid access developer known e.g. fromgraphic arts. Short processing times may provide an opportunity to makeuse in the sound laboratory of compact processors.

[0055] White light sources such as tungsten lamps have conventionallybeen used to record analog soundtracks. Accordingly, the nativesensitivity of many silver halide emulsions in the blue region of theelectromagnetic spectrum (e.g. 380-500 nm) has been sufficient for suchwhite light recording. Where additional speed is desired for white lightrecording or where emulsions are used which lack sufficient nativesensitivity in the visible light region, sound recording films have beensensitized for analog recording with blue and/or green sensitizing dyes.Otherwise digital soundtrack recording is typically performed byexposing a sound recording film to a modulated coherent radiation lightsource having a narrow band width, such as a modulated laser beam orlight emitting diode or diode array. So sound recording films have beenmade which are optimally spectrally sensitized to provide a peaksensitivity to match a particular digital recording device, along withproviding adequate sensitivity for recording anolog soundtracks withwhite light sources.

[0056] In another embodiment a soundtrack image in a motion pictureprint film may, apart from originating from the panchromaticblack-and-white sound recording film spectrally sensitized both aboveand below 600 nm, alternatively comprise e.g. a soundtrack negative in achromogenic soundtrack recording film by exposing said film andprocessing said exposed film with a color developer process to form adye soundtrack negative, and printing a soundtrack onto anegative-working motion picture color print film by exposing the motionpicture print film through the dye soundtrack negative and processingthe exposed print film to form a positive soundtrack. Thelight-sensitive emulsion layer of the sound recording film preferablycomprises green or red light-sensitive silver halide emulsion grains anda cyan or magenta dye-forming coupler in the substantial absence ofyellow dye-forming coupler. Most preferred in that case is alight-sensitive emulsion layer of the sound recording film comprisinggreen and red light-sensitive silver halide emulsion grains and cyan andmagenta dye-forming couplers in the substantial absence of yellowdye-forming coupler as has been disclosed in U.S. Pat. No. 5,856,057.Dyes presented above may advantageously be used in an antihalation layerof such a chromogenic sound film.

EXAMPLES

[0057] While the present invention will hereinafter be described inconnection with preferred embodiments thereof, it will be understoodthat it is not intended to limit the invention to those embodiments.

[0058] Emulsion A:

[0059] Making use of the double jet precipitation technique a 100% AgClemulsion having an particle diameter of 0.6 μ was precipitated. Afterwashing and redispersing the emulsion contained about 1.2 mole ofAgNO₃/kg. The weight ratio of gelatin to AgNO₃ amounts to 0.4.

[0060] The emulsion was divided into 5 equal portions and chemicallysensitized in the following way :

[0061] Chemical Sensitization of Part A-1 :

[0062] This emulsion part was sensitized at a pH of 5.1. First of all 3mmole of KI/mole of AgNO₃ were added. After 5 minutes 3.7 μmole ofHAuCl₄ per mole of AgNO₃; 9.7 μmole of toluene thiosulphonic acid permole of AgNO₃ and 12 μmole of Na₂S₂O₃ per mole of AgNO₃ were added.Chemical sensitization was performed at 70 C. for approximately 1.5hours.

[0063] Chemical Sensitization of Part A-2 :

[0064] Just as for Part A-1, but immediately after chemicalsensitization, 0.44 mmole of compound (I.1) was added per mole of Ag.

[0065] Chemical Sensitization of Part A-3 :

[0066] Just as for Part A-1, but immediately after chemicalsensitization, 0.3 mmole of compound (I.10) per mole of Ag was added.

[0067] Chemical Sensitization of Part A-4 :

[0068] Just as for Part A-1 but immediately after chemical sensitization0.37 mmole of compound (I.8) per mole of Ag was added.

[0069] Chemical Sensitization of Part A-5 :

[0070] Just as for Part A-1 but immediately after chemical sensitization0.2 mmole of compound (I.12) per mole of Ag was added.

[0071] Photographic evaluation of these emulsion Parts A1 to A5 wasperformed by incorporating the emulsions in a blue-sensitive recordingmaterial having following composition : Layer 1-Antihalation undercoatGelatin 1000 mg/m2 Solid Particle Antihalation Dye (AH-1) 280 mg/m2Cetiol S 200 mg/m2 Layer 2-Blue Sensitive Layer Gelatin 2100 mg/m2Emulsion Parts (A1-A6) 4050 mg/m2 Blue-sensitizer S-1 1.3 mg/m2 Yellowdye-forming Coupler Y-1 1345 mg/m2 Soluble Filter Dye FD-1 120 mg/m2Layer 3-Protective Overcoat Gelatin 800 mg/m2 Poly-dimethylsiloxanelubricant (BAYER) 20 mg/m2 Polymethylmethacrylate matte beads (3 μm) 3mg/m2 Cetiol 5 50 mg/m2 Fluoro Chemical FC143 from 3M 30 mg/m2 Anionicsurfactant (dodecyl arylsulphonate, sodium salt) 20 mg/m2Triazin-hardener T-S 88 mg/m2

[0072] These photographic materials were coated on a subbed polyethyleneterephthalate support.

[0073] Formulae corresponding with the compounds AH-1, AH-2, Y-1, FD-1and T-S have been given hereinafter.

[0074] Photographic properties and, more particularly, latent imagestability, was evaluated by exposing the materials through a step wedgefor 10 ms. These materials were processed later on according to thestandard Kodak ECP-2B Color Print Development Process. Between exposingand processing the different materials were kept at room temperatureduring 10 days. In order to be able to give an indication for latentimage stability, the same materials were processed immediately afterexposure, the figure thus obtained offering a reference value:differences in sensitivity between a material processed immediatelyafter exposure and a material processed 10 days after exposure,expressed as “Δ LogE” was taken as a measure for latent image stability.Data thus obtained have been summarized in Table I. TABLE I Chemicalsensitization sensitivity ΔLog E A-1 comparative 119 −66 A-2 invention90 −3 A-3 invention 101 −6 A-4 invention 92 −4 A-5 invention 82 −4

[0075] Emulsion B:

[0076] Making use of the double jet precipitation technique a 100% AgClemulsion having an particle diameter of 0.3 μ was precipitated. Afterwashing and redispersing the emulsion contained about 1.2 mole ofAgNO₃/kg. The weight ratio of gelatin to AgNO₃ amounts to 0.4.

[0077] The emulsion was divided into 2 equal portions and chemicallysensitized in the following way :

[0078] Chemical Sensitization of Part B-1 :

[0079] This emulsion part was sensitized at a pH of 5.1. First of all 3mmole of KI/mole of AgNO₃ were added. After 5 minutes 10 μmole of HAuCl₄per mole of AgNO₃; 16 μmole of toluene thiosulphonic acid per mole ofAgNO₃ and 8.75 μmole of Na₂S₂O₃ per mole of AgNO₃ were added. Chemicalsensitization was performed at 70 C. for approximately 1.5 hours.

[0080] Chemical Sensitization of Part B-2 :

[0081] Just as for Part B-1, but immediately after chemicalsensitization, 0.88 mmole of compound (I.1) per mole Ag was added.

[0082] A photographic blue-sensitive recording material having thefollowing composition is produced on a subbed polyester support. Layer1-antihalation undercoat Gelatin 1000 mg/m2 Solid Particle AntihalationDye (AH-1) 280 mg/m2 Cetiol S (oilformer, surfactant from HENKEL) 200mg/m2 Layer 2-Blue Sensitive Layer Gelatin 2100 mg/m2 Emulsion (PartsB1-B2) 4050 mg/m2 Blue-sensitizer S-1 1.3 mg/m2 Yellow dye-formingCoupler Y-1 1345 mg/m2 Soluble Filter Dye FD-1 120 mg/m2 Layer3-Protective Overcoat Gelatin 800 mg/m2 Polydimethylsiloxane lubricant(BAYER) 20 mg/m2 Polymethylmethacrylate matte beads (3 μ) 3 mg/m2 CetiolS (oilformer, surfactant from HENKEL) 50 mg/m2 Fluoro Chemical FC143from 3M 30 mg/m2 Anionic surfactant (dodecyl arylsulphonate, sodiumsalt) 20 mg/m2 Triazin-hardener T-S (see above) 88 mg/m2

[0083] The formula of blue-sensitizer S-1 has been given hereinafter:

[0084] The latent image stability was evaluated by exposing thematerials through a step wedge for 10 ms and processing these materialsaccording to the standard Kodak ECP-2B Color Print Development Process.

[0085] Between exposure and processing the different materials were keptat room temperature during 10 days. In order to obtain a referencefigure, the same materials were processed immediately after exposure.

[0086] The difference in sensitivity between a material processedimmediately after exposure and a material processed 10 days afterexposure, called “Δ LogE”, was taken as a measure for latent imagestability. TABLE II Chemical sensitization sensitivity ΔLog E B-1comparison 123 −69 B-2 invention 115 −8

[0087] Having described in detail preferred embodiments of the currentinvention, it will now be apparent to those skilled in the art thatnumerous modifications can be made therein without departing from thescope of the invention as defined in the appending claims.

What is claimed is:
 1. A method of preparing an emulsion in an aqueousmedium containing a protective colloid, said method comprising asconsecutive steps precipitating cubic emulsion crystals rich in silverchloride; flocculating, washing and redispersing by addition of a bindermaterial; adjusting pH and pAg; adding, prior to chemical sensitization,a compound releasing iodide ions, adding as chemical sensitizing agentsconsecutively, a gold compound, an oxidizing compound and a compoundreleasing sulphur; chemically sensitizing said cubic emulsion crystals;characterized in that, after ending said chemically sensitizing step,addition of a compound according to the general formula (I) isperformed,

wherein R represents a substituted aryl and wherein M represents ahydrogen atom, an alkali metal atom or an ammonium group.
 2. Methodaccording to claim 1, wherein said compound according to the generalformula (I) is an acetamidophenyl mercaptotetrazole.
 3. Method accordingto claim 1, wherein said compound according to the general formula (I)is added to the said emulsion in an amount in a range of from 0.01 up to1 mmole per mole of silver halide.
 4. Method according to claim 2,wherein said compound according to the general formula (I) is added tothe said emulsion in an amount in a range of from 0.01 up to 1 mmole permole of silver halide.
 5. Method according to claim 1, wherein saidcompound releasing iodide ions is selected from the group consisting ofan alkali iodide salt, an I₃-complex and a fine-grained silver iodideemulsion, having emulsion grains of not more than 0.050 μm, and is addedin an amount in order to have an average amount of iodide in the cubiccrystals rich in silver chloride in an amount of not more than 3 mole %,based on silver.
 6. Method according to claim 2, wherein said compoundreleasing iodide ions is selected from the group consisting of an alkaliiodide salt, an I₃-complex and a fine-grained silver iodide emulsion,having emulsion grains of not more than 0.050 μm, and is added in anamount in order to have an average amount of iodide in the cubiccrystals rich in silver chloride in an amount of not more than 3 mole %,based on silver.
 7. Method according to claim 3, wherein said compoundreleasing iodide ions is selected from the group consisting of an alkaliiodide salt, an I₃-complex and a fine-grained silver iodide emulsion,having emulsion grains of not more than 0.050 μm, and is added in anamount in order to have an average amount of iodide in the cubiccrystals rich in silver chloride in an amount of not more than 3 mole %,based on silver.
 8. Method according to claim 1, wherein said protectivecolloid is selected from the group consisting of gelatin, silica sol,starch or a mixture thereof.
 9. Method according to claim 1, whereinsaid binder material is a hydrophilic colloidal polymeric binderselected from the group consisting of gelatin, poly-N-vinylpyrrolidone,dextranes, cellulose compounds and derivatives thereof and copolymers ofvinylidene chloride-methylacrylate-itaconic acid ormethyl(meth)acrylate-butadiene-itaconic acid or a mixture thereof. 10.Method according to claim 8, wherein gelatin is selected from the groupof consisting of natural gelatin and modified gelatin.
 11. Methodaccording to claim 9, wherein gelatin is selected from the group ofconsisting of natural gelatin and modified gelatin.
 11. Method accordingto claim 1, wherein said cubic emulsion crystals rich in silver chloridehave an average edge length of from 0.1 μm up to 1.0 μm.
 12. Methodaccording to claim 2, wherein said cubic emulsion crystals rich insilver chloride have an average edge length of from 0.1 μm up to 1.0 μm.13. Method according to claim 3, wherein said cubic emulsion crystalsrich in silver chloride have an average edge length of from 0.1 μm up to1.0 μm.
 14. Method according to claim 1, wherein said cubic emulsiongrains rich in silver chloride have at least 50 mole % of silverchloride, based on silver; and wherein silver bromide, if present, ispresent in a molar amount of not more than 20 mole %, based on silver.15. Method according to claim 2, wherein said cubic emulsion grains richin silver chloride have at least 50 mole % of silver chloride, based onsilver; and wherein silver bromide, if present, is present in a molaramount of not more than 20 mole %, based on silver.
 16. Method accordingto claim 3, wherein said cubic emulsion grains rich in silver chloridehave at least 50 mole % of silver chloride, based on silver; and whereinsilver bromide, if present, is present in a molar amount of not morethan 20 mole %, based on silver.
 17. A silver halide material comprisingone or more emulsions prepared according to the method according toclaim
 1. 18. A silver halide material comprising one or more emulsionsprepared according to the method according to claim
 2. 19. A silverhalide material comprising one or more emulsions prepared according tothe method according to claim
 3. 20. A silver halide material comprisingone or more emulsions prepared according to the method according toclaim
 5. 21. A silver halide material comprising one or more emulsionsprepared according to the method according to claim
 8. 22. A silverhalide material comprising one or more emulsions prepared according tothe method according to claim
 9. 23. A silver halide material comprisingone or more emulsions prepared according to the method according toclaim
 11. 24. A silver halide material comprising one or more emulsionsprepared according to the method according to claim 14.